Macrocyclic tetrapyrroles are essential to life. In nature, they play important roles in living organisms, such as oxygen transportation and photosynthesis. Pentynoic acids are versatile precursors for preparing pyrrolines and higher homologues. Our research group has been using pentynoic acids in the synthesis of macrocyclic tetrapyrroles for many years. This thesis describes two synthetic projects related to macrocyclic tetrapyrroles involving two different types of pentynoic acids.

Vitamin B12 is the most complex of all the vitamins. Its carbon core, cobyric acid, belongs to the corrin family of tetrapyrroles. Cobyric acid, comprising four five-membered hetereocyclic rings A, B, C, and D, is organized around a central cobalt atom and the periphery is substituted with methyl, acetamide and propionamide substituents. For the synthesis of cobyric acid, four different alkyne acids can be used as building blocks. A new route of enantioselective and diasteroselective synthesis of an alkyne acid ring-D precursor was developed. The chiral center was induced with the Corey-Bakshi-Shibata reagent with high enantioseletivity (91% e.e.). An Ireland-Claisen rearrangement was used as the key strategy leading to high diastereoselectivity (d.r.>11:1).

Chlorins are potential candidates for cancer photodynamic therapy. Although chlorins are ubiquitous natural products, many are difficult to isolate. Also, there are limited numbers of total syntheses of chlorins. A new route to the synthesis of chlorins was developed in this research. Thus, condensation of bis-formyldihydrodipyrrins and dipyrromethanes in the proper oxidation state gave chlorins directly. These new chlorins are good candidates for testing the relationship between vertical localization in cell membranes and photochemical activity.